Add branching-strategy skill with next and create actions

Version-aware branch naming (X.Y.Z.Q/{TASK_CODE}-{FEATURE}-{SEQ}),
branch creation from origin/test with origin/main fallback, and the
PR-into-test merge rule. Ships a TypeScript CLI (next, create) plus
shell modules (loggers, base, cli) run via Taskfile.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

scripts/Taskfile.yml

@@ -0,0 +1,39 @@
+# https://taskfile.dev
+
+version: "3"
+
+includes:
+  base: ./.scripts/base/Taskfile.yml
+  cli: ./.scripts/cli/Taskfile.yml
+
+tasks:
+  default:
+    cmds:
+      - task --list-all
+    silent: true
+
+  build:
+    desc: Compile TypeScript source to dist/
+    cmds:
+      - task: cli:build
+    silent: true
+
+  next:
+    desc: |
+      Compute the next branch name (X.Y.Z.Q/{TASK_MANAGEMENT_CODE}-{FEATURE_X}-{SEQ}).
+      Usage: task next -- --task-key="IIAA-123" --topic="api-cleanup" [--base=…] [--repo-dir=…]
+    cmds:
+      - task: cli:next
+        vars:
+          CLI_ARGS: "{{ .CLI_ARGS }}"
+    silent: true
+
+  create:
+    desc: |
+      Compute and create the next branch locally (never pushes).
+      Usage: task create -- --task-key="IIAA-123" --topic="api-cleanup" [--base=…] [--repo-dir=…]
+    cmds:
+      - task: cli:create
+        vars:
+          CLI_ARGS: "{{ .CLI_ARGS }}"
+    silent: true